Digital Modem from BG5ROJ: Part 1

After a few weeks waiting for my new toy, it finally arrived today! The new Digital Modem from BG5ROJ. A brand new product from a Chinese amateur radio. I bought the modem directly from their website :

Let me tell you that at 165.99$ USD plus shipping, it is a real bargain! The overall quality is also amazing!


I will do many tests in the next days,

so I will my post my review in many parts.


First view: The hardware

Actual specification

  • Supported Modes: PSK, RTTY, CW (new modes may be added by updating the firmware)
  • Input and Output Ports: USB-HOST, Mini-Din6, 3.5mm Stereo
  • Display: 3.5″ 128×64 LCD
  • Power Supply: 2 AA-Size Battery or single cell Lithium battery
  • Power Consumption: Less than 0.5W
  • Size: 160 x 65 x 27 mm

B1 is a push button to select et invoke menu items. B2 is also a push button but also a scrolling wheel to select options. To turn ON the unit, the user must push B1 and B2 forward for 2 seconds. It is essential if the user do not want his unit turned ON by accident when stored with all other gears when travelling.


The unit is very nice build. The screen is really sharp and clear, very easy to read as you can see. The unit is approximately 5 in. X 2.5 in. X 1 in. A very small form factor for all of us who expect to carry their gears in with less space.


The modem hopefully is very easy to integrate with the transceiver, especially with the Yaesu FT-817. It uses the standard DATA pinout found on the transceiver. The DATA cable is provided with the modem at no extra cost. The USB connector is used to connect the keyboard….. hopefully a USB keyboard !!! Very easy to find…. even the smaller one!!! The USB connector is also used for futur firmware upgrades. At the moment, I using firmware version 1.03. The manufacturer already told me that new firmware with other new functions will be available later…. so what about a piece of hardware that will host new feature! What a joy!

The modem supports a direct IQ signal input from a SDR receiver. To activate it, you need to change the signal source configuration in the main menu. The demodulated audio is sent to the phone jack, and the demodulated text data is showed on the LCD.


There is also a PHONE and AUX conenctors. This 3.5mm phone jack is used to monitor the receiving audio from your external transceiver, or to monitor the
transmitting audio tone (modulated tone) from the modem itself. Depending on the different input signal source configured in
the main menu, this 3.5mm phone jack plays different monitoring tasks:

A. External Data: <In Receive> It monitors the received audio tone from your transceiver <In Transmit> It’s muted.
B. Internal MIC: <In Receive> It’s muted. <In Transmit> It monitors the transmitted audio (modulated) tone from the modem itself.
C. External I/Q : <In Receive> It monitors the decoded I/Q audio signal tone from your transceiver. <In Transmit> It’s muted.
D. Internal TRX Mod: <In Receive> It monitors the decoded I/Q audio signal tone from the TRX module. <In Transmit> It’s muted.

The AUX connector is for a CW key. You can use a CW key instead of a standard USB keyboard for sending commands or characters. Let’s say you answer a CQ sent in PSK31, but by using your CW key. The modem will translate your CW in PSK31 as well as in other mode too….. like the Elecraft KX3 and K3 already do. It is easy to connect to the modem to other transceivers even if they do not have a DATA out capability.

20160418_203644145_iOS Their a small speaker to hear the BEEP command confirmation. The DC input (8V-26V) is for charging Lithium internal batteries when used. The user can choose between using 2 AA Lithium batteries, standard 2 AA batteries. 8 hours of operation is at the moment expected by using 2 fresh AA Alkaline batteries.

The built-in charging circuitry in intended for Lithium battery only, not for AA batteries. The unit will automatic detect the inserted battery category, and it will not charge the AA batteries. The lithium battery is not supplied in the package due to the air shipment regulations, you may need to locate one by yourself. However, a USB-DC cable is supplied in the package, and you may need a cell phone charger with USB port to charge the internal lithium battery at the same time.

If a lithium battery is used, you do not need the AA batteries, and you do not need to replace it after the power is used up. Instead, you need to re-charge it by connecting a USB-DC cable (also provided at no extra cost) with one end to your cell phone charger adapter and the other end to the DC IN port of the modem. The AA batteries are really convenient to locate. However, the unit will not charge it up even if you connect the USB-DC cable in. Do not forget to take the AA batteries OUT if you put this digital modem aside for long.

Take a look on the upper right part of the picture, there is also a small micro SD memory card slot. It lets you save your configuration settings, or even all the QSO’s you will do with the modem when operating.

A very nice addition!


A 128 MB micro SD card is also supplied with the modem at no extra charge.


An internal Lithium batteries is for clock time and date when the unit is turned off.

A plenty of menu functions is also available. This will let the user to choose between different protocols (BPSK, RTTY, etc.), and many other functions and features to customize the modem.

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OK that’s it for now! I will post more review in my next post.

Stay tuned everybody!


Jeff | VA2SS